TiNi-Based Bi-Metallic Shape-Memory Alloy by Laser-Directed Energy Deposition

In this study, laser-directed energy deposition was applied to build a Ti-rich ternary Ti–Ni–Cu shape-memory alloy onto a TiNi shape-memory alloy substrate to realize the joining of the multifunctional bi-metallic shape-memory alloy structure. The cost-effective Ti, Ni, and Cu elemental powder blend...

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Bibliographic Details
Published in:Materials Vol. 15; no. 11; p. 3945
Main Authors: Chen, Yitao, Ortiz Rios, Cesar, McLain, Braden, Newkirk, Joseph W., Liou, Frank
Format: Journal Article
Language:English
Published: Switzerland MDPI AG 01.06.2022
MDPI
Subjects:
Alloys
Austenite
Bonding strength
Copper
Deposition
Differential scanning calorimetry
Digital imaging
Intermetallic compounds
Laser applications
Lasers
Martensitic transformations
Material properties
Nickel base alloys
Nickel compounds
Particle size
Precipitates
Raw materials
Shape effects
Shape memory alloys
Steel
Substrates
Temperature
Tensile tests
Titanium compounds
Transformation temperature
United States > US
shape-memory alloys
additive manufacturing
joining of metals
elemental powders
directed energy deposition
ISSN:1996-1944, 1996-1944
Online Access:Get full text
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Summary:In this study, laser-directed energy deposition was applied to build a Ti-rich ternary Ti–Ni–Cu shape-memory alloy onto a TiNi shape-memory alloy substrate to realize the joining of the multifunctional bi-metallic shape-memory alloy structure. The cost-effective Ti, Ni, and Cu elemental powder blend was used for raw materials. Various material characterization approaches were applied to reveal different material properties in two sections. The as-fabricated Ti–Ni–Cu alloy microstructure has the TiNi phase as the matrix with Ti2Ni secondary precipitates. The hardness shows no high values indicating that the major phase is not hard intermetallics. A bonding strength of 569.1 MPa was obtained by tensile testing, and digital image correlation reveals the different tensile responses of the two sections. Differential scanning calorimetry was used to measure the phase-transformation temperatures. The austenite finishing temperature of higher than 80 °C was measured for the Ti–Ni–Cu alloy section. For the TiNi substrate, the austenite finishing temperature was tested to be near 47 °C at the bottom and around 22 °C at the upper substrate region, which is due to the repeated laser scanning that acts as annealing on the substrate. Finally, the multiple shape-memory effect of two shape-memory alloy sides was tested and identified.
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USDOE
SC0018879
ISSN:1996-1944
1996-1944
DOI:10.3390/ma15113945